Trump officials denied a request made by California governor Gavin Newsom for a major presidential disaster declaration, Brian Ferguson, a spokesman for the Governor's Office of Emergency Services, said late on Wednesday night.
He did not reveal the reason why the request had been rejected but said the state plans to launch an appeal against the decision. Governor Newsom had written to the president on 28 September asking him for financial assistance.
Six major blazes - one of which became the single largest fire in state history after it chewed up almost 300,000 acres - have wrought havoc across the state, killing at least 30 people, with thousands more forced to flee their homes.
Local officials estimate that just over 9,000 buildings have been destroyed since September, while the damage to infrastructure has been calculated at $229 million.
California officials made public the funding rejection as Mr Trump called on voters in the solidly Democrat state to back him for reelection, telling them: ‘WHAT THE HELL DO YOU HAVE TO LOSE!!!"
A major disaster declaration would have allowed California to share the cost of cleaning up the fires with the government.
According to Mr Ferguson, California did not put an exact figure on how much it might cost the state to carry out repairs although it was likely to be in the hundreds of millions of dollars.
“The true cost won’t be known for months or years afterward,” he said.
He added: “What the state is looking for is the highest level of federal support, which requires the highest bars be cleared. But we feel our case for those requirements has been met.”
In the midst of another heatwave in the state, thousands in wine country were without power on Thursday after providers turned off supplies due to fears of further fires.
Pacific Gas and Electric started cutting power Wednesday evening to more than 45,000 customers — about 100,000 people — mainly in the Sierra Nevada foothills and the San Francisco Bay Area.
Some restorations began Thursday afternoon, and by evening the number of customers without power was about 30,000, the utility said. All power was expected to be restored by Friday night.
Many in wine country north of San Francisco were feeling drained by what seems like a never-ending wildfire season in the region.
More than 8,500 wildfires have burned more than 6,400 square miles (16,000 square kilometres) in California since the start of the year. Most have occurred since mid-August.
In southern California, a brush fire on Thursday near Redlands triggered a small evacuation as it grew to more than 100 acres (40 hectares). It was about 50 per cent contained.
Hot winds up to 55 mph were expected to heighten the threat of blazes throughout the San Francisco Bay Area, which has already seen some of the worst wildfires in state history.
The National Weather Service issued heat advisories through Friday, with temperatures expected to reach triple digits in many parts of the state.
Additional reporting by Associated Press